6 Ambitious Airplanes That Never Flew

Aeronautics companies and defense contractors are always looking for the next great aircraft design, and those massive government grants let them launch incredibly ambitious projects. This has given us some of the greatest aircraft to ever grace the skies, but sometimes the design overreaches the grasp. These are some of the grand plane projects that were canceled before a prototype ever flew.

Advertisement - Continue Reading Below

1Lockheed L-133 Starjet

Lockheed Martin

The end of World War II was the dawn of the fighter jet. The German Messerschmitt Me-262 entered military service in 1944, while the first American fighter jet used by the United States Army Air Forces (the predecessor to the U.S. Air Force) was the Lockheed P-80 Shooting Star, introduced the next year. It turns out, however, that the United States had been working on a design for a jet-powered fighter six years earlier, before the Japanese even attacked Pearl Harbor.

It was called the Lockheed L-133 Starjet. The L-133 design outlined a fighter powered by two Lockheed L-1000 turbojets that would make use of a canard design (see the small forewings) to assist with lift. The Army Air Forces rejected the proposal in 1942, and Lockheed instead developed the simpler and more practical P-80.

Advertisement - Continue Reading Below

Advertisement - Continue Reading Below

2Saunders-Roe SR.177

Emoscopes/Wikimedia

The Saunders-Roe SR.177 was an ambitious attempt by the British Royal Air Force to develop a combination jet- and rocket-powered interceptor to defend against the threat of Soviet bombers. But a new military budget laid out by the U.K Parliament in 1957 canceled the project.

The research paved the way for the similar Saunders-Roe SR.53, two of which were built and underwent flight tests. The second prototype of the SR.53 crashed in an aborted takeoff on its 12th flight test, exploding on impact and killing the pilot.

Advertisement - Continue Reading Below

Advertisement - Continue Reading Below

3WS-125

Final Gear

As the Cold War iced over in the 1950s, the Air Force wanted a nuclear-powered super-long-range strategic bomber. The Soviet Union wanted one, too, but both countries struggled to find a way to incorporate shielding strong enough to protect the crew from the radiation of a nuclear reactor in their plane.

In the U.S., GE partnered with Convair to build a nuclear bomber, while Pratt & Whitney worked with Lockheed. Neither team succeeded. After a billion dollars went into the design and development of a nuclear aircraft engine, the project was canceled in 1961. Some ideas just aren't meant to get off the ground.

Advertisement - Continue Reading Below

Advertisement - Continue Reading Below

4Lockheed L-2000

San Diego Air & Space Museum

The L-2000 was Lockheed's attempt to secure a government contract to build a supersonic plane. The United States wanted a supersonic passenger jet to rival the Anglo-French Concorde and the Soviet Tupolev Tu-144.

Lockheed and Boeing had done a number of "paper studies" on SST designs, and both were eager to secure funding from the government to develop a prototype. After both companies' designs were rigorously examined, the Boeing 2707 was selected for funding in 1967, but the U.S. killed the program in 1971 before the two prototypes could be completed (see below). The L-2000 was never built at all.

Advertisement - Continue Reading Below

Advertisement - Continue Reading Below

5Boeing 2707

The 2707 was the United States' first try at developing a commercial SST. The aircraft's design had a drooping nose similar to the Concorde's, though it was intended to be much larger and fly much faster than the European jet. Designs accounted for a maximum capacity of 300 passengers and a cruising speed of Mach 3.

The original design for the Boeing 2707 also incorporated a swing-wing platform, allowing the wings to stay straight on takeoff and landing for increased stability but retract into a swept position for improved aerodynamics at supersonic speeds. The mechanism needed proved too heavy, however, and engineers were forced to scrap the idea and redesign the plane with a traditional delta wing.

Construction started in the late '60s on two 2707 prototypes, but trouble developing a metal skin that could withstand the extreme heat of supersonic speed, as well as environmental and noise pollution concerns, led the government to pull funding for the project in 1971.

Advertisement - Continue Reading Below

Advertisement - Continue Reading Below

6High Speed Civil Transport

The High Speed Civil Transport (HSCT) was the focus of NASA's High-Speed Research program, which was supported by multiple American aerospace companies through the 1990s. NASA began developing technology for the supersonic passenger jet in 1990. The HSCT was to travel at a cruising speed of Mach 2.4 and have room for 300 passengers.

The program carried on the research of the Concorde, Tu-144, and American SST program, though development of the HSCT was canceled in 1999. More recently, NASA and Lockheed Martin announced a partnership to work on a new supersonic demonstrator aircraft, one designed to reduce the noise of a sonic boom.

A Part of Hearst Digital Media
Popular Mechanics participates in various affiliate marketing programs, which means we may get paid commissions on editorially chosen products purchased through our links to retailer sites.